SAVANNAH, Georgia (CNN) --Bats and river rats cried out unsettling squeaks as Creepy Pub Crawl tour guide John Lile spooked wide-eyed tourists with ghost stories along the misty riverfront in the southern city of Savannah, Georgia.

"You're gonna bite all your fingernails," Lile said to a young woman in the back of the group.

Or so he hopes. He, like the tour guides of 31 other local ghost tours, makes his living scaring tourists while ushering them around the historic colonial city, pausing to point out where Savannah's otherworldly residents reside.

Walking tours are an excellent way for tourists to learn about the city's tumultuous history, Erica Backus of the Savannah Area Convention and Visitor's Bureau said of the 6.5 million visitors a year. "History makes the city more sensitive to spirits," said Backus, who added that at least half of the tourists who go on walking tours, take a ghost tour.

Whether you're out to have some fun, or to study the facts, Savannah's ghost tours show off the unique personality of Georgia's oldest city, which embodies traditional Southern hospitality and charm but also revels in its rough-and-tumble past.

Shannon Scott, creator of the Sixth Sense Savannah ghost tour, lures tourists around the city and back to his house.

A battleground during the American Revolution, captured by Sherman during the Civil War (but spared the wrath the Union visited on Atlanta), the City's historical district also weathered hurricanes, fires and two devastating outbreaks of yellow fever. Savannah's port-city origins (it lies on the Savannah River, just inland from the Atlantic Ocean) incorporate an early population of colonists, slaves, voodooists, sailors, traders and pirates with unique social and religious beliefs. These elements combined make a fitting backdrop for spooky ghost tales and unexplained phenomenon.

One of the city's daytime ghost tours focuses heavily on history. Tourist Nancy Rupert from Holstein, Iowa, said she connected the city's difficult past to the hauntings described in the tour. "So many people were killed here. It can't be just coincidence," she said as she followed the Sixth Sense Savannah tour, created by parapsychologist Shannon Scott.

Scott prides himself on research and fact checking, but also said he's a believer.

"People on my tour have [seen ghosts] and although that's not a guarantee of the tour, we do have sightings on the tour," he said.

According to Scott, his residence -- the last stop on the tour -- is home to a ghost he calls Liza (as well as his specter-sensing dog Mina). To keep with the theme, he recently acquired a bed frame made from old cemetery gates he says are haunted.

Grave beginnings

It's not strange in Savannah to sleep on parts of a cemetery. The city's unofficial saying, "Savannah was built on its dead," pays homage to its grave beginnings.

Scott's tour starts in the parking lot of a diner where the asphalt hides the past. "Beneath us," the guide said, "is the corner boundary of an old slave cemetery."

After Colonial Park closed in 1852, renovations salvaged headstones dislodged by hurricanes and vandalism, said Robert Edgerly of See Savannah Walking Tours.

Other stories detail how settlements and battlefields left unorganized colonial gravesites scattered around the city. Lile estimated the historic section of Savannah covers seven cemeteries, with at least 9,000 graves.

"I wouldn't be surprised if there were more," said Robert Edgerly of See Savannah Walking Tours. "There's at least 14,000 documented graves in Colonial Park Cemetery alone," Edgerly said, but it is hard to know for sure as not all of them lie within the current boundaries of the cemetery.

Luciana Spracher, author of "Lost Savannah" and "A History of Thunderbolt, Georgia," said that although she couldn't name more than a few cemeteries that were built over as the city of Savannah developed, some streets and buildings do exist on land where graves once were, or still are.

"I know there were several small cemeteries that were moved, and there's always the possibility that unmarked graves weren't moved," she said. Spracher says there was once a 16-plot Jewish cemetery at the intersection of Oglethorpe Avenue and Bull Street, where only a small marker betrays the graves lying under the busy streets.

With so many graves underfoot it's only fitting that a walking ghost tour would stop at a cemetery.

The city's central cemetery is the setting for one of Savannah's most famous ghost stories, that of Rene Asche Rondolier (or Renee Rondolia Asch, depending on who tells the story), an orphan purportedly disfigured and feared by many, who was said to have called Colonial Park his home in the early 1800s.

Tales of the afterlife

Other people called it "Rene's Playground." But Rene is not remembered for having much fun.

According to Lile's rendition, the townspeople accused Rene of murdering two girls and leaving their bodies in the cemetery. An angry mob then dragged Rene to the nearby swamps, lynched him and left him for dead. In the days following the lynching, Lile said more bodies turned up in Colonial Park, and the townspeople blamed the ghost of Rene.

Scott, who researched the story at great length, offered a more detailed tale of Rene. He described Rene's disproportionate seven-foot statue and his subsequent confinement and display in a blockhouse by the port. Scott says dignitaries and important visitors came to see Rene in the blockhouse. Regarding Rene's murderous ghost, Scott says, "Two other children and one woman were found following his lynching, each on separate days."

More recently, Savannah's ghost-telling tradition received national attention with the 1994 best-selling book "Midnight in the Garden of Good and Evil," the story of a journalist's encounter with art collector Jim Williams and other city denizens. Although the book spotlighted Savannah as one of America's most haunted destinations, several other books also focus specifically on hauntings in the city.

Resident and author Margaret Wayt DeBolt said she helped lay the foundation for the city's ghost tour industry with her 1984 book "Savannah Spectres and other Strange Tales," and a charity ghost tour of the city. Her book chronicles the city's ghostly legacy and names several spooky sites, which "Ghost Talk, Ghost Walk" used as the basis of Savannah's first modern ghost tour.

Once an inn and tavern frequented by pirates and sailors, the long-standing Pirate House is now a popular restaurant.

One haunted spot listed in the book and frequented by tours is the Pirate House. Legend has it that Captain Flint of Robert Louis Stevenson's "Treasure Island" (1883) died there, screaming for rum. Many sailors frequented the Pirate house in the late 1700s and early 1800s, according to DeBolt, but nobody knows for sure if Captain Flint was actually there.

Another frequent stop on Savannah ghost tours is the 17Hundred90 house, now a restaurant, bar and inn. Rumor says the house has more than one ghost -- a lady in the inn, a servant in the kitchen and a sailor in the restaurant. Another ghostly must-see is the birth home of John Mercer, location of several mysterious deaths including the one in the book, "Midnight in the Garden of Good and Evil."

Girl scouts and ghost-hunters alike visit the birth house of Juliette Gordon Low, founder of the Girl Scouts. The ghost of General Gordon, her father, appeared there to escort his dying wife Nellie to the afterlife, according to DeBolt. Others reported seeing the ghost of Nellie Gordon after hours when the house is closed, said DeBolt.

After hearing a few of Savannah's spooky stories and sampling spirits of all kinds, many tourists end a ghost tour with more questions than answers.

Hunting for answers

For the curious, Scott said he has an answer. He points to the earth for an unconventional explanation of ghostly phenomenon. Parapsychologists consider Savannah's sand to be a "geomagnetic anomaly," he said.

It "has an electromagnetic charge greater than other areas. The human spirit is equated to magnetic energy so either spirits are drawn here because of that or they have a hard time leaving because of that," he said.

"Savannah is probably one of 10 cities in the country that has a long track record of parapsychologists, demonologists and witches studying it," he said.

A recent study by British scientists offers another explanation for things that go bump in the night. The study attributes ghostly experiences to an extremely low sound frequency called infrasound that humans normally can't hear. A controlled experiment on 750 people listening to music laced with infrasound concluded that infrasound makes people feel anxious, scared and sad, and sometimes produces spine-tingling chills -- much like the reactions associated with haunted houses and other spooky places.

Tour guide John Lile, left, tells the legend of Rene Asche Rondolier to tourists off River Street in Savannah, Georgia.

Richard Lord, an acoustic scientist working at the National Physical Laboratory in Middlesex, England, was part of the team studying infrasound. He said that although their experiment dealt with music and infrasound inside a concert hall, "there are often natural sources."

When asked if a coastal city like Savannah might have more infrasound than other areas, he said, "It's feasible to say that wind and tidal effect might have some influence on infrasound."

Experiments and theories aside, half the fun of a Savannah ghost tour can be seeing who believes and who doesn't.

"I consider the tour to be an entertainment tour," Lile said. "Whether I do or don't believe in ghosts, the important thing to me is that there are smiles on people's faces."